The right seat

Went to the cinema tonight (saw horror film Oculus which was very good). They now have allocated seating. This leads to all sorts of dilemmas for a British person: the cinema was not very full, but my allocated seat was directly behind two people. Do I sit in it, when normally I would allow more space? Or do I not sit in it and thus risk being in a seat that has been allocated to someone else? I preferred being trusted to find my own seat to be honest.